Import bovine manual from CEDET trunk

Ref
http://lists.gnu.org/archive/html/emacs-devel/2012-11/msg00419.html
and preceding discussion

Imported from
bzr://cedet.bzr.sourceforge.net/bzrroot/cedet/code/trunk
doc/texi/semantic/bovine.texi

doc/misc/ChangeLog

+2012-12-13  Eric Ludlam  <zappo@gnu.org>
+	    David Ponce  <david@dponce.com>
+	    Richard Kim  <emacs18@gmail.com>
+
+	* bovine.texi: New file, imported from CEDET trunk.
+
 2012-12-12  Glenn Morris  <rgm@gnu.org>
 
 	* flymake.texi (Customizable variables, Locating the buildfile):

doc/misc/bovine.texi

+\input texinfo  @c -*-texinfo-*-
+@c %**start of header
+@setfilename bovine.info
+@set TITLE  Bovine parser development
+@set AUTHOR Eric M. Ludlam, David Ponce, and Richard Y. Kim
+@settitle @value{TITLE}
+
+@c *************************************************************************
+@c @ Header
+@c *************************************************************************
+
+@c Merge all indexes into a single index for now.
+@c We can always separate them later into two or more as needed.
+@syncodeindex vr cp
+@syncodeindex fn cp
+@syncodeindex ky cp
+@syncodeindex pg cp
+@syncodeindex tp cp
+
+@c @footnotestyle separate
+@c @paragraphindent 2
+@c @@smallbook
+@c %**end of header
+
+@copying
+This manual documents Bovine parser development in Semantic
+
+Copyright @copyright{} 1999, 2000, 2001, 2002, 2003, 2004 Eric M. Ludlam
+Copyright @copyright{} 2001, 2002, 2003, 2004 David Ponce
+Copyright @copyright{} 2002, 2003 Richard Y. Kim
+
+@quotation
+Permission is granted to copy, distribute and/or modify this document
+under the terms of the GNU Free Documentation License, Version 1.1 or
+any later version published by the Free Software Foundation; with the
+Invariant Sections being list their titles, with the Front-Cover Texts
+being list, and with the Back-Cover Texts being list.  A copy of the
+license is included in the section entitled ``GNU Free Documentation
+License''.
+@end quotation
+@end copying
+
+@ifinfo
+@dircategory Emacs
+@direntry
+* Semantic bovine parser development: (bovine).
+@end direntry
+@end ifinfo
+
+@iftex
+@finalout
+@end iftex
+
+@c @setchapternewpage odd
+@c @setchapternewpage off
+
+@ifinfo
+This file documents parser development with the bovine parser generator
+@emph{Infrastructure for parser based text analysis in Emacs}
+
+Copyright @copyright{} 1999, 2000, 2001, 2002, 2003, 2004 @value{AUTHOR}
+@end ifinfo
+
+@titlepage
+@sp 10
+@title @value{TITLE}
+@author by @value{AUTHOR}
+@vskip 0pt plus 1 fill
+Copyright @copyright{} 1999, 2000, 2001, 2002, 2003, 2004 @value{AUTHOR}
+@page
+@vskip 0pt plus 1 fill
+@insertcopying
+@end titlepage
+@page
+
+@c MACRO inclusion
+@include semanticheader.texi
+
+
+@c *************************************************************************
+@c @ Document
+@c *************************************************************************
+@contents
+
+@node top
+@top @value{TITLE}
+
+The @dfn{bovine} parser is the original @semantic{} parser, and is an
+implementation of an @acronym{LL} parser.  It is good for simple
+languages.  It has many conveniences making grammar writing easy.  The
+conveniences make it less powerful than a Bison-like @acronym{LALR}
+parser.  For more information, @inforef{top, the Wisent Parser Manual,
+wisent}.
+
+Bovine @acronym{LL} grammars are stored in files with a @file{.by}
+extension.  When compiled, the contents is converted into a file of
+the form @file{NAME-by.el}.  This, in turn is byte compiled.
+@inforef{top, Grammar Framework Manual, grammar-fw}.
+
+@menu
+* Starting Rules::              The starting rules for the grammar.
+* Bovine Grammar Rules::        Rules used to parse a language
+* Optional Lambda Expression::  Actions to take when a rule is matched
+* Bovine Examples::             Simple Samples
+* GNU Free Documentation License::  
+* Index::                       
+@end menu
+
+@node Starting Rules
+@chapter Starting Rules
+
+In Bison, one and only one nonterminal is designated as the ``start''
+symbol.  In @semantic{}, one or more nonterminals can be designated as
+the ``start'' symbol.  They are declared following the @code{%start}
+keyword separated by spaces.  @inforef{start Decl, ,grammar-fw}.
+
+If no @code{%start} keyword is used in a grammar, then the very first
+is used.  Internally the first start nonterminal is targeted by the
+reserved symbol @code{bovine-toplevel}, so it can be found by the
+parser harness.
+
+To find locally defined variables, the local context handler needs to
+parse the body of functional code.  The @code{scopestart} declaration
+specifies the name of a nonterminal used as the goal to parse a local
+context, @inforef{scopestart Decl, ,grammar-fw}.  Internally the
+scopestart nonterminal is targeted by the reserved symbol
+@code{bovine-inner-scope}, so it can be found by the parser harness.
+
+@node Bovine Grammar Rules
+@chapter Bovine Grammar Rules
+
+The rules are what allow the compiler to create tags from a language
+file.  Once the setup is done in the prologue, you can start writing
+rules.  @inforef{Grammar Rules, ,grammar-fw}.
+
+@example
+@var{result} : @var{components1} @var{optional-semantic-action1})
+       | @var{components2} @var{optional-semantic-action2}
+       ;
+@end example
+
+@var{result} is a nonterminal, that is a symbol synthesized in your grammar.
+@var{components} is a list of elements that are to be matched if @var{result}
+is to be made.  @var{optional-semantic-action} is an optional sequence
+of simplified Emacs Lisp expressions for concocting the parse tree.
+
+In bison, each time an element of @var{components} is found, it is
+@dfn{shifted} onto the parser stack.  (The stack of matched elements.)
+When all @var{components}' elements have been matched, it is
+@dfn{reduced} to @var{result}.  @xref{(bison)Algorithm}.
+
+A particular @var{result} written into your grammar becomes
+the parser's goal.  It is designated by a @code{%start} statement
+(@pxref{Starting Rules}).  The value returned by the associated
+@var{optional-semantic-action} is the parser's result.  It should be
+a tree of @semantic{} @dfn{tags}, @inforef{Semantic Tags, ,
+semantic-appdev}.
+
+@var{components} is made up of symbols.  A symbol such as @code{FOO}
+means that a syntactic token of class @code{FOO} must be matched.
+
+@menu
+* How Lexical Tokens Match::    
+* Grammar-to-Lisp Details::     
+* Order of components in rules::  
+@end menu
+
+@node How Lexical Tokens Match
+@section How Lexical Tokens Match
+
+A lexical rule must be used to define how to match a lexical token.
+
+For instance:
+
+@example
+%keyword FOO "foo"
+@end example
+
+Means that @code{FOO} is a reserved language keyword, matched as such
+by looking up into a keyword table, @inforef{keyword Decl,
+,grammar-fw}.  This is because @code{"foo"} will be converted to
+@code{FOO} in the lexical analysis stage.  Thus the symbol @code{FOO}
+won't be available any other way.
+
+If we specify our token in this way:
+
+@example
+%token <symbol> FOO "foo"
+@end example
+
+then @code{FOO} will match the string @code{"foo"} explicitly, but it
+won't do so at the lexical level, allowing use of the text
+@code{"foo"} in other forms of regular expressions.
+
+In that case, @code{FOO} is a @code{symbol}-type token.  To match, a
+@code{symbol} must first be encountered, and then it must
+@code{string-match "foo"}.
+
+@table @strong
+@item Caution:
+Be especially careful to remember that @code{"foo"}, and more
+generally the %token's match-value string, is a regular expression!
+@end table
+
+Non symbol tokens are also allowed.  For example:
+
+@example
+%token <punctuation> PERIOD "[.]"
+
+filename : symbol PERIOD symbol
+         ;
+@end example
+
+@code{PERIOD} is a @code{punctuation}-type token that will explicitly
+match one period when used in the above rule.
+
+@table @strong
+@item Please Note:
+@code{symbol}, @code{punctuation}, etc., are predefined lexical token
+types, based on the @dfn{syntax class}-character associations
+currently in effect.
+@end table
+
+@node Grammar-to-Lisp Details
+@section Grammar-to-Lisp Details
+
+For the bovinator, lexical token matching patterns are @emph{inlined}.
+When the grammar-to-lisp converter encounters a lexical token
+declaration of the form:
+
+@example
+%token <@var{type}> @var{token-name} @var{match-value}
+@end example
+
+It substitutes every occurrences of @var{token-name} in rules, by its
+expanded form:
+
+@example
+@var{type} @var{match-value}
+@end example
+
+For example:
+
+@example
+%token <symbol> MOOSE "moose"
+
+find_a_moose: MOOSE
+            ;
+@end example
+
+Will generate this pseudo equivalent-rule:
+
+@example
+find_a_moose: symbol "moose"   ;; invalid syntax!
+            ;
+@end example
+
+Thus, from the bovinator point of view, the @var{components} part of a
+rule is made up of symbols and strings.  A string in the mix means
+that the previous symbol must have the additional constraint of
+exactly matching it, as described in @ref{How Lexical Tokens Match}.
+
+@table @strong
+@item Please Note:
+For the bovinator, this task was mixed into the language definition to
+simplify implementation, though Bison's technique is more efficient.
+@end table
+
+@node Order of components in rules
+@section Order of components in rules
+
+If a rule has multiple components, order is important, for example
+
+@example
+headerfile : symbol PERIOD symbol
+           | symbol
+           ;
+@end example
+
+would match @samp{foo.h} or the @acronym{C++} header @samp{foo}.
+The bovine parser will first attempt to match the long form, and then
+the short form.  If they were in reverse order, then the long form
+would never be tested.
+
+@c @xref{Default syntactic tokens}.
+
+@node Optional Lambda Expression
+@chapter Optional Lambda Expressions
+
+The @acronym{OLE} (@dfn{Optional Lambda Expression}) is converted into
+a bovine lambda.  This lambda has special short-cuts to simplify
+reading the semantic action definition.  An @acronym{OLE} like this:
+
+@example
+( $1 )
+@end example
+
+results in a lambda return which consists entirely of the string
+or object found by matching the first (zeroth) element of match.
+An @acronym{OLE} like this:
+
+@example
+( ,(foo $1) )
+@end example
+
+executes @code{foo} on the first argument, and then splices its return
+into the return list whereas:
+
+@example
+( (foo $1) )
+@end example
+
+executes @code{foo}, and that is placed in the return list.
+
+Here are other things that can appear inline:
+
+@table @code
+@item $1
+The first object matched.
+
+@item ,$1
+The first object spliced into the list (assuming it is a list from a
+non-terminal).
+
+@item '$1
+The first object matched, placed in a list.  i.e. @code{( $1 )}.
+
+@item foo
+The symbol @code{foo} (exactly as displayed).
+
+@item (foo)
+A function call to foo which is stuck into the return list.
+
+@item ,(foo)
+A function call to foo which is spliced into the return list.
+
+@item '(foo)
+A function call to foo which is stuck into the return list in a list.
+
+@item (EXPAND @var{$1} @var{nonterminal} @var{depth})
+A list starting with @code{EXPAND} performs a recursive parse on the
+token passed to it (represented by @samp{$1} above.)  The
+@dfn{semantic list} is a common token to expand, as there are often
+interesting things in the list.  The @var{nonterminal} is a symbol in
+your table which the bovinator will start with when parsing.
+@var{nonterminal}'s definition is the same as any other nonterminal.
+@var{depth} should be at least @samp{1} when descending into a
+semantic list.
+
+@item (EXPANDFULL @var{$1} @var{nonterminal} @var{depth})
+Is like @code{EXPAND}, except that the parser will iterate over
+@var{nonterminal} until there are no more matches.  (The same way the
+parser iterates over the starting rule (@pxref{Starting Rules}). This
+lets you have much simpler rules in this specific case, and also lets
+you have positional information in the returned tokens, and error
+skipping.
+
+@item (ASSOC @var{symbol1} @var{value1} @var{symbol2} @var{value2} @dots{})
+This is used for creating an association list.  Each @var{symbol} is
+included in the list if the associated @var{value} is non-@code{nil}.
+While the items are all listed explicitly, the created structure is an
+association list of the form:
+
+@example
+((@var{symbol1} . @var{value1}) (@var{symbol2} . @var{value2}) @dots{})
+@end example
+
+@item (TAG @var{name} @var{class} [@var{attributes}])
+This creates one tag in the current buffer.
+
+@table @var
+@item name
+Is a string that represents the tag in the language.
+
+@item class
+Is the kind of tag being create, such as @code{function}, or
+@code{variable}, though any symbol will work.
+
+@item attributes
+Is an optional set of labeled values such as @w{@code{:constant-flag t :parent
+"parenttype"}}.
+@end table
+
+@item  (TAG-VARIABLE @var{name} @var{type} @var{default-value} [@var{attributes}])
+@itemx (TAG-FUNCTION @var{name} @var{type} @var{arg-list} [@var{attributes}])
+@itemx (TAG-TYPE @var{name} @var{type} @var{members} @var{parents} [@var{attributes}])
+@itemx (TAG-INCLUDE @var{name} @var{system-flag} [@var{attributes}])
+@itemx (TAG-PACKAGE @var{name} @var{detail} [@var{attributes}])
+@itemx (TAG-CODE @var{name} @var{detail} [@var{attributes}])
+Create a tag with @var{name} of respectively the class
+@code{variable}, @code{function}, @code{type}, @code{include},
+@code{package}, and @code{code}.
+See @inforef{Creating Tags, , semantic-appdev} for the lisp
+functions these translate into.
+@end table
+
+If the symbol @code{%quotemode backquote} is specified, then use
+@code{,@@} to splice a list in, and @code{,} to evaluate the expression.
+This lets you send @code{$1} as a symbol into a list instead of having
+it expanded inline.
+
+@node Bovine Examples
+@chapter Examples
+
+The rule:
+
+@example
+any-symbol: symbol
+          ;
+@end example
+
+is equivalent to
+
+@example
+any-symbol: symbol
+            ( $1 )
+          ;
+@end example
+
+which, if it matched the string @samp{"A"}, would return
+
+@example
+( "A" )
+@end example
+
+If this rule were used like this:
+
+@example
+%token <punctuation> EQUAL "="
+@dots{}
+assign: any-symbol EQUAL any-symbol
+        ( $1 $3 )
+      ;
+@end example
+
+it would match @samp{"A=B"}, and return
+
+@example
+( ("A") ("B") )
+@end example
+
+The letters @samp{A} and @samp{B} come back in lists because
+@samp{any-symbol} is a nonterminal, not an actual lexical element.
+
+To get a better result with nonterminals, use @asis{,} to splice lists
+in like this:
+
+@example
+%token <punctuation> EQUAL "="
+@dots{}
+assign: any-symbol EQUAL any-symbol
+        ( ,$1 ,$3 )
+      ;
+@end example
+
+which would return
+
+@example
+( "A" "B" )
+@end example
+
+@node GNU Free Documentation License
+@appendix GNU Free Documentation License
+
+@include fdl.texi
+
+@node Index
+@unnumbered Index
+@printindex cp
+
+@iftex
+@contents
+@summarycontents
+@end iftex
+
+@bye
+
+@c Following comments are for the benefit of ispell.
+
+@c  LocalWords:  bovinator inlined